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High Efficiency Microturbine with Integral Heat Recovery

Introduction

The U.S. economic market potential for distributed generation is significant. This market, however, remains mostly untapped in the commercial and small industrial buildings that are well suited for microturbines.

Gas turbines have many advantages, including high power density, light weight, clean emissions, fuel flexibility, low vibration, low maintenance, high reliability, and excellent durability. These power generation systems are frequently used for aviation, utility power, and remote oil and gas applications.

This project is developing a 370 kW gas-fueled microturbine that will attract additional markets because of its increased energy efficiency and reduced capital cost, which is expected to be approximately $600 per kW. The microturbine technology will maximize usable exhaust energy and achieve ultra-low emissions levels.

The initial target for the C370 microturbine is the distributed generation market using existing fuel infrastructure, including fossil fuels, such as natural gas and diesel, as well as renewable fuels, such as landfill gas, digester gas, and syngas.

High Efficiency Microturbine

Project Description

The objective of this project is to demonstrate a microturbine based distributed generation system with increased efficiency, reduced emissions, and improved customer value. The highest risk technical challenges were addressed early in the project and many components from current Capstone products are being used to accelerate development and ensure commercial success.

The project is using a modified Capstone C200 compressor and turbine assembly to act as the low-pressure section of a two-shaft turbine system. This results in an electrical output of 250 kW. A new high-temperature, high-pressure compressor and turbine will act as the second assembly. After an intercooler and the high-pressure assembly are added, the electrical output will increase to 370 kW.

Pathways

Capstone Turbine Corporation is leading this project. Oak Ridge National Laboratory (ORNL) and the NASA Glenn Research Center are supporting Capstone on specific project objectives. ORNL will assist with the high-pressure recuperator and high-temperature radial turbine materials. NASA Glenn will evaluate a larger air bearing design for the high-speed generator.

The first phase of the project is to design and demonstrate the elements of the C370 CHP system that represent the greatest challenges of technical development. Capstone will design and integrate a low-pressure compressor and turbine system using a modified version of the C200; high-pressure, high-temperature compressor and turbine system; a combustion system; an intercooler; and high-pressure recuperator to create a two-shaft C370 engine.

Capstone will integrate heat recovery technology to complete the C370 CHP system. This system will be tested and demonstrated in the field to validate performance.

Commercialization

The C200 was developed in part with support from the U.S. Department of Energy’s Advanced Microturbine Systems program. The 200 kW microturbine has a net electrical efficiency of 33%; therefore, achieving 42% net electrical efficiency and 85% total system efficiency in a CHP application for the C370 is feasible. Such high efficiency combined with emissions levels that are below California Air Resources Board (CARB) requirements and competitive capital cost of $600 per kW is expected to make the C370 an attractive product in the marketplace.

Capstone will use its current distributor and original equipment manufacturer (OEM) business model to directly market the C370 microturbine CHP system, which will be offered for sale within 12 months after successful demonstration of the project.

The planned level of U.S. sales for 2020 is approximately 500 units. Using this projection, the total C370 U.S. installed base is estimated to be 2,700 units by 2020. This would account for 1 gigawatt (GW) of electric generating capacity.